The present invention relates generally to adjustment mechanisms for power tools, and more particularly, to a flexible height-adjustment mechanism useful in adjusting the height of a router mounted within a router table.
Routers are popular woodworking tools which are widely used by professionals and amateur woodworkers alike. A router primarily consists of a motor mounted in a housing which drives a central shaft. A wide variety of cutting and shaping bits may be mounted on the central shaft of the router and used for cutting different profiles in wood.
A router may be used in two different manners. First of all, it may be used where its shaft and associated cutting bit are directed downwardly so that the bit cuts into a piece of wood while the woodworker drags the router along the top surface of the wood. A router may also be used in a direction opposite that described above, i.e. in an "upside-down" manner where the router drive shaft and bit are directed upwardly. This mounting is almost always used when the router is mounted into what is known in the art as a router table. The router cutting bit is directed upwardly through an opening in the top of the router table and the woodworker must move his wood along the top of the router table into contact with cutting bit, rather than moving the router along the wood as described above. In using a router table, the woodworker must set the height at which the router cutting bit projects above the router table surface.
One router gaining in popularity and particularly useful to most woodworkers is a plunge router. As its name implies, a plunge router may be moved up and down into contact with a piece of wood. The typical plunge router has a base mounted to it and is spaced apart from the router housing by one or more plunger rods which fit within recesses of the router housing. This structure which permits the router housing (and its cutting bit) to be slid along the plunge rods toward the base so that the cutting bit is brought into contact with the wood upon which the base sits.
In order to adjust the particular "depth" of the cut desired from a plunge router, such a router is typically equipped with a long, threaded adjustment rod which projects up from the router base and through a portion of the router housing. A nut is threaded onto this adjustment rod and provides a "stop" which limits the travel of the router housing along its plunge rods. In order to set the cutting depth, a woodworker turns the nut along the threaded rod to set the depth of cut of the router cutting bit. This adjustment is most often done by using by an open-ended wrench which creates an inconvenience to the woodworker. When a plunge router is mounted upside down within a router table, the access to the adjustment rod and associated depth stop nut is constrained and often the operating height of the router must be set prior to mounting the router in the table. If the height is not correct, the router must be taken off the table and reset. This procedure is time-consuming.
In recognition of the time-consuming nature of this characteristic of routers, those skilled in the art have developed after-market and custom router height-adjustment mechanisms. One such adjustment mechanism is described in the September 1995 issue of Wood Magazine. This mechanism uses a section of rigid tubing with a pair of threaded nuts wedged into one end and a knob for grasping and turning the mechanism located at the other end. Although effective, this type of mechanism is not without its own particular problems.
For example, the tubing used must be rigid so as to effectively turn the height-adjustment rod and move the router and its cutting bit up or down in the table. The tubing may wind up located within the router table at an inconvenient location which requires the woodworker to awkwardly sketch to gain access to and operate it. Additionally, the rigid tubing height-adjustment mechanism is not a universal solution because certain routers, such as the Porter-Cable 7539, have their housings configured in a manner does not permit it to accept a height-adjustment knob because the knob interferes with the router housing. Still other routers may have portions of their housings extending over the threaded rod, making the attachment of a rigid height-adjustment extension rod sleeve virtually impossible.
The present invention is directed to a flexible router height-adjustment mechanism which overcomes the aforementioned disadvantages. In doing so, it utilizes a minimum number of parts and provides a mechanism for adjusting the height of virtually any design of plunge router regardless of the configuration of the router housing.
In a router height-adjustment mechanism incorporating the principles of the present invention, an elongated height-adjustment extension is provided, the extension including a flexible sleeve having two opposing engagement ends, one end being configured to engage the threaded height-adjustment rod of a plunger router and the other end being configured to engage a driving tool such as a ratchet ball or power screwdriver.
The flexible sleeve may include a length of flexible tubing, such as flexible PVC tubing and may also have an exterior reinforcement sleeve in the form of a coil spring arranged coaxial therewith. The sleeve is capable, in one embodiment, of significant deflection when installed so that it may extend over any interfering portions of a plunge router housing.
Accordingly, it is a general object of the present invention to provide an improved router height-adjustment mechanism which attaches to the height-adjustment rod of a plunge router and which provides an extension away of the rod for easy access and which avoids interference with any portion of the router housing.
Another object of the present invention is to provide a flexible router height-adjustment mechanism which engages a router depth adjustment rod on a plunge router and provides a flexible shaft extension which may be coupled to a power driving tool for motor-driven adjustment of the router operating depth.
A further object of the present invention is to provide a kit of parts for use in converting an existing router into a plunge router having improved height-adjustment capabilities, in which the kit of parts includes a flexible sleeve with a reinforcing collar extending thereover, the sleeve having a threaded engagement end which is adapted to engage the height-adjustment rod of the router and further having a driving end having a drive socket which is adapted to receive the shaft of a driving tool such as a power screwdriver or ratchet ball.
These and other objects, features and advantages of the present invention will be apparent from a reading of the following detailed description, taken in conjunction with the accompanying drawings wherein like reference numerals refer to like parts.